The EPA has recently promulgated as part of the Clean Air Act a major reduction in nitrogen oxides (NOX) emissions with compliance scheduled for May 1, 2003 in 22 eastern states and the District of Columbia. For the electrical utility industry specifically, a 75% reduction in the current permissible emission has been established which is equivalent to 0.15 lb NOX per million BTU's. The major method of compliance for the utilities will be selective catalytic reduction (SCR) as NOX reductions of 80% to 90% have been proven in Germany and Japan where these regulations have existed for fifteen years.
Predominantly, coal-fired utilities are affected by this regulation. In Europe and Asia where this technology has been employed for a long time, their coals tend to contain low sulfur (less than 1.5% SO.sub.2) whereas United States coals are significantly higher in sulfur content. The level of total sulfur ranges from 1.13% total sulfur for coal from the Pittsburgh seam in Washington, Pa. to a level of 8.2% total sulfur for coal from the Bevier seam in Henry, Mo. Operation of the SCR's overseas has presented only minor problems whereas in the U.S., several problems have occurred due to the higher sulfur content.